%s
\n\ \n\ \n" static int initialize_tls_session_client(int peer_socket, const char *hostname, gnutls_session_t *session, gnutls_certificate_credentials_t *x509_cred); static int initialize_tls_session_server(int peer_socket, gnutls_session_t *session, gnutls_certificate_credentials_t *x509_cred); static int read_http_request(FILE *client_fd, char *request, size_t length); static void send_bad_request(FILE *client_fd); static void send_forwarding_failure(FILE *client_fd); static void tls_send_invalid_cert_message(gnutls_session_t session); static void transfer_data(int client, int server); static int read_from_write_to(int from, int to); static void transfer_data_tls(int client, int server, gnutls_session_t client_session, gnutls_session_t server_session); static int read_from_write_to_tls(gnutls_session_t from, gnutls_session_t to, size_t buffer_size); static int connect_to_host(const char *hostname, const char *port); static int parse_request(const char *buffer, char *host, char *port, int *version_minor); void handle_connection(int client_socket) { int server_socket; FILE *client_fd, *server_fd; char buffer[MAX_REQUEST_LINE]; char host[MAX_REQUEST_LINE]; char port[5 + 1]; int version_minor; /* HTTP/1.x */ int result; /* client_x509_cred is used when talking to the client (acting as a TSL * server), server_x509_cred is used when talking to the server (acting as * a TSL client). */ gnutls_certificate_credentials_t client_x509_cred, server_x509_cred; gnutls_session_t client_session, server_session; /* initialize_tls_session_*() called? - used for goto out */ int client_session_init, server_session_init; /* gnutls_handshake() called? - used for goto out */ int client_session_started, server_session_started; /* Validation failed? If yes we need to send the special "invalid" * certificate. */ int validation_failed; LOG(LOG_DEBUG, "new connection"); server_socket = -1; client_fd = NULL; server_fd = NULL; client_session_init = 0; server_session_init = 0; client_session_started = 0; server_session_started = 0; validation_failed = 0; client_fd = fdopen(client_socket, "a+"); if (NULL == client_fd) { LOG_PERROR(LOG_WARNING, "fdopen(): client failed"); goto out; } /* Read request line (CONNECT ..) and headers (they are discarded). */ result = read_http_request(client_fd, buffer, sizeof(buffer)); if (-1 == result) { /* Read error. */ LOG(LOG_WARNING, "read_http_request(): client read error"); goto out; } else if (-2 == result) { /* EOF */ LOG(LOG_WARNING, "read_http_request(): client EOF"); send_bad_request(client_fd); goto out; } if (0 != parse_request(buffer, host, port, &version_minor)) { LOG(LOG_WARNING, "bad request: %s", buffer); send_bad_request(client_fd); goto out; } LOG(LOG_DEBUG, "target: %s:%s (HTTP 1.%d)", host, port, version_minor); /* Connect to proxy server or directly to server. */ if (NULL != global_proxy_host && NULL != global_proxy_port) { LOG(LOG_DEBUG, "connecting to %s:%s", global_proxy_host, global_proxy_port); server_socket = connect_to_host(global_proxy_host, global_proxy_port); } else { LOG(LOG_DEBUG, "connecting to %s:%s", host, port); server_socket = connect_to_host(host, port); } if (-1 == server_socket) { LOG(LOG_WARNING, "failed to connect to server"); send_forwarding_failure(client_fd); goto out; } server_fd = fdopen(server_socket, "a+"); if (NULL == server_fd) { LOG_PERROR(LOG_WARNING, "fdopen(): server failed"); send_forwarding_failure(client_fd); goto out; } /* Connect to proxy if requested (command line option). */ if (NULL != global_proxy_host && NULL != global_proxy_port) { fprintf(server_fd, "CONNECT %s:%s HTTP/1.0\r\n", host, port); fprintf(server_fd, "\r\n"); /* Read response line from proxy server. */ result = read_http_request(server_fd, buffer, sizeof(buffer)); if (-1 == result) { /* Read error. */ LOG(LOG_WARNING, "read_http_request(): proxy read error"); send_forwarding_failure(client_fd); goto out; } else if (-2 == result) { /* EOF */ LOG(LOG_WARNING, "read_http_request(): proxy EOF"); send_forwarding_failure(client_fd); goto out; } /* Check response of proxy server. */ if (0 != strncmp(buffer, "HTTP/1.0 200", 12)) { LOG(LOG_WARNING, "bad proxy response: %s", buffer); send_forwarding_failure(client_fd); goto out; } } LOG(LOG_DEBUG, "connection to server established"); /* If the -u option is used and we don't know this hostname's server * certificate then just pass through the connection and let the client * verify the server certificate. */ if (global_passthrough_unknown) { char path[1024]; FILE *file = NULL; if (-2 == server_certificate_file(&file, host, path, sizeof(path))) { /* We've established a connection, tell the client. */ fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n"); fprintf(client_fd, "\r\n"); fflush(client_fd); LOG(LOG_DEBUG, "transferring data"); /* Proxy data between client and server until one side is done * (EOF or error). */ transfer_data(client_socket, server_socket); LOG(LOG_DEBUG, "finished transferring data"); goto out; } /* server_certificate_file() may have opened the file, close it. */ if (NULL != file) { fclose(file); } } /* Initialize TLS client credentials to talk to the server. */ result = initialize_tls_session_server(server_socket, &server_session, &server_x509_cred); if (0 != result) { LOG(LOG_WARNING, "initialize_tls_session_server() failed"); send_forwarding_failure(client_fd); goto out; } server_session_init = 1; LOG(LOG_DEBUG, "starting server TLS handshake"); /* Try to establish TLS handshake between us and server. */ result = gnutls_handshake(server_session); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_WARNING, "server TLS handshake failed: %s", gnutls_strerror(result)); send_forwarding_failure(client_fd); goto out; } server_session_started = 1; LOG(LOG_DEBUG, "server TLS handshake finished"); /* Make sure the server certificate is valid and known. */ if (0 != verify_tls_connection(server_session, host)) { LOG(LOG_ERROR, "server certificate validation failed!"); /* We send the error message over our TLS connection to the client, * but with an invalid certificate. No data is transfered from/to the * target server. */ validation_failed = 1; } /* Initialize TLS server credentials to talk to the client. */ result = initialize_tls_session_client(client_socket, /* use a special host if the server * certificate was invalid */ (validation_failed) ? "invalid" : host, &client_session, &client_x509_cred); if (0 != result) { LOG(LOG_WARNING, "initialize_tls_session_client() failed"); send_forwarding_failure(client_fd); goto out; } client_session_init = 1; /* We've established a connection, tell the client. */ fprintf(client_fd, "HTTP/1.0 200 Connection established\r\n"); fprintf(client_fd, "\r\n"); fflush(client_fd); LOG(LOG_DEBUG, "starting client TLS handshake"); /* Try to establish TLS handshake between client and us. */ result = gnutls_handshake(client_session); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_WARNING, "client TLS handshake failed: %s", gnutls_strerror(result)); send_forwarding_failure(client_fd); goto out; } client_session_started = 1; LOG(LOG_DEBUG, "client TLS handshake finished"); /* Tell the client that the verification failed. Shouldn't be necessary as * the client should terminate the connection because he received the * invalid certificate but better be sure. */ if (validation_failed) { tls_send_invalid_cert_message(client_session); goto out; } LOG(LOG_DEBUG, "transferring TLS data"); /* Proxy data between client and server until one side is done (EOF or * error). */ transfer_data_tls(client_socket, server_socket, client_session, server_session); LOG(LOG_DEBUG, "finished transferring TLS data"); out: /* Close TLS sessions if necessary. Use GNUTLS_SHUT_RDWR so the data is * reliable transmitted. */ if (0 != server_session_started) { gnutls_bye(server_session, GNUTLS_SHUT_RDWR); } if (0 != client_session_started) { gnutls_bye(client_session, GNUTLS_SHUT_RDWR); } if (0 != server_session_init) { gnutls_deinit(server_session); gnutls_certificate_free_credentials(server_x509_cred); } if (0 != client_session_init) { gnutls_deinit(client_session); gnutls_certificate_free_cas(client_x509_cred); gnutls_certificate_free_keys(client_x509_cred); gnutls_certificate_free_credentials(client_x509_cred); } /* Close connection to server/proxy. */ if (NULL != server_fd) { fclose(server_fd); } else if (-1 != server_socket) { close(server_socket); } LOG(LOG_DEBUG, "connection to server closed"); /* Close connection to client. */ if (NULL != client_fd) { fclose(client_fd); } else { close(client_socket); } LOG(LOG_DEBUG, "connection to client closed"); LOG(LOG_DEBUG, "connection finished"); } static int initialize_tls_session_client(int peer_socket, const char *hostname, gnutls_session_t *session, gnutls_certificate_credentials_t *x509_cred) { int result; int use_invalid_cert; char path[1024]; /* The "invalid" hostname is special. If it's used we send an invalid * certificate to let the client know something is wrong. */ use_invalid_cert = (0 == strcmp(hostname, "invalid")); if (0 != proxy_certificate_path(hostname, path, sizeof(path))) { LOG(LOG_ERROR, "initialize_tls_session_client(): \ failed to get proxy certificate path"); return -1; } result = gnutls_certificate_allocate_credentials(x509_cred); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_client(): \ gnutls_certificate_allocate_credentials(): %s", gnutls_strerror(result)); return -1; } /* Load proxy CA file, this CA "list" is send to the client. */ if (!use_invalid_cert) { result = gnutls_certificate_set_x509_trust_file(*x509_cred, PROXY_CA_FILE, GNUTLS_X509_FMT_PEM); if (0 >= result) { LOG(LOG_ERROR, "initialize_tls_session_client(): can't read CA file: '%s'", PROXY_CA_FILE); gnutls_certificate_free_credentials(*x509_cred); return -1; } } /* If the invalid hostname was specified do nothing, we use a self-signed * certificate in this case. */ /* And certificate for this website and proxy's private key. */ if (!use_invalid_cert) { result = gnutls_certificate_set_x509_key_file(*x509_cred, path, PROXY_KEY_FILE, GNUTLS_X509_FMT_PEM); /* If the invalid hostname was specified load our special "invalid" * certificate. */ } else { result = gnutls_certificate_set_x509_key_file(*x509_cred, PROXY_INVALID_CERT_FILE, PROXY_KEY_FILE, GNUTLS_X509_FMT_PEM); } if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_client(): \ can't read server certificate ('%s') or key file ('%s'): %s", path, PROXY_KEY_FILE, gnutls_strerror(result)); gnutls_certificate_free_credentials(*x509_cred); /* Could be a missing certificate. */ return -2; } gnutls_certificate_set_dh_params(*x509_cred, global_tls_dh_params); result = gnutls_init(session, GNUTLS_SERVER); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_client(): gnutls_init(): %s", gnutls_strerror(result)); gnutls_certificate_free_credentials(*x509_cred); return -1; } result = gnutls_priority_set(*session, global_tls_priority_cache); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_client(): gnutls_priority_set(): %s", gnutls_strerror(result)); gnutls_deinit(*session); gnutls_certificate_free_credentials(*x509_cred); return -1; } result = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE, *x509_cred); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_client(): gnutls_credentials_set(): %s", gnutls_strerror(result)); gnutls_deinit(*session); gnutls_certificate_free_credentials(*x509_cred); return -1; } gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket); return 0; } static int initialize_tls_session_server(int peer_socket, gnutls_session_t *session, gnutls_certificate_credentials_t *x509_cred) { int result; result = gnutls_certificate_allocate_credentials(x509_cred); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_server(): \ gnutls_certificate_allocate_credentials(): %s", gnutls_strerror(result)); return -1; } result = gnutls_init(session, GNUTLS_CLIENT); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_server(): gnutls_init(): %s", gnutls_strerror(result)); gnutls_certificate_free_credentials(*x509_cred); return -1; } gnutls_priority_set(*session, global_tls_priority_cache); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_server(): gnutls_priority_set(): %s", gnutls_strerror(result)); gnutls_deinit(*session); gnutls_certificate_free_credentials(*x509_cred); return -1; } result = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE, *x509_cred); if (GNUTLS_E_SUCCESS != result) { LOG(LOG_ERROR, "initialize_tls_session_server(): gnutls_credentials_set(): %s", gnutls_strerror(result)); gnutls_deinit(*session); gnutls_certificate_free_credentials(*x509_cred); return -1; } gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket); return 0; } /* Read HTTP request line and headers (ignored). * * On success 0 is returned, -1 on client error, -2 on unexpected EOF. */ static int read_http_request(FILE *client_fd, char *request, size_t length) { char buffer[MAX_REQUEST_LINE]; if (NULL == fgets(request, (int)length, client_fd)) { if (ferror(client_fd)) { LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()"); return -1; } return -2; } while (NULL != fgets(buffer, sizeof(buffer), client_fd)) { /* End of header. */ if (0 == strcmp(buffer, "\n") || 0 == strcmp(buffer, "\r\n")) { break; } } if (ferror(client_fd)) { LOG_PERROR(LOG_WARNING, "read_http_request(): fgets()"); return -1; } return 0; } static void send_bad_request(FILE *client_fd) { #define RESPONSE_ERROR "400 Bad Request" #define RESPONSE_MSG "Your browser sent an invalid request." fprintf(client_fd, HTTP_RESPONSE_FORMAT, RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_MSG); #undef RESPONSE_ERROR #undef RESPONSE_MSG } static void send_forwarding_failure(FILE *client_fd) { #define RESPONSE_ERROR "503 Forwarding failure" #define RESPONSE_MSG "Failed to connect to server, check logs." fprintf(client_fd, HTTP_RESPONSE_FORMAT, RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_MSG); #undef RESPONSE_ERROR #undef RESPONSE_MSG } static void tls_send_invalid_cert_message(gnutls_session_t session) { #define RESPONSE_ERROR "500 Internal Server Error" #define RESPONSE_MSG "Server certificate validation failed, check logs." int result; char buffer[sizeof(HTTP_RESPONSE_FORMAT) - 1 /* '\0' */ - 4 * 2 /* four %s */ + (sizeof(RESPONSE_ERROR) - 1 /* '\0' */) * 3 + sizeof(RESPONSE_MSG) - 1 /* '\0' */ + 1 /* '\0' */]; result = snprintf(buffer, sizeof(buffer), HTTP_RESPONSE_FORMAT, RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_ERROR, RESPONSE_MSG); if (result < 0) { LOG_PERROR(LOG_ERROR, "tls_send_invalid_cert_message(): snprintf failed"); return; } else if ((size_t)result >= sizeof(buffer)) { LOG(LOG_ERROR, "tls_send_invalid_cert_message(): snprintf buffer too short"); return; } gnutls_record_send(session, buffer, sizeof(buffer) - 1); /* don't send trailing '\0' */ #undef RESPONSE_ERROR #undef RESPONSE_MSG } /* Transfer data between client and server sockets until one closes the * connection. */ static void transfer_data(int client, int server) { struct pollfd fds[2]; fds[0].fd = client; fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR; fds[0].revents = 0; fds[1].fd = server; fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR; fds[1].revents = 0; for (;;) { int result = poll(fds, 2, -1 /* no timeout */); if (result < 0) { LOG_PERROR(LOG_ERROR, "transfer_data(): poll()"); return; } /* Data available from client. */ if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) { if (0 != read_from_write_to(client, server)) { /* EOF (or other error) */ break; } } /* Data available from server. */ if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) { if (0 != read_from_write_to(server, client)) { /* EOF (or other error) */ break; } } /* Client closed connection. */ if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) { break; } /* Server closed connection. */ if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) { break; } } } /* Read available data from socket from and write it to socket to. At maximum * 4096 bytes are read/written. */ static int read_from_write_to(int from, int to) { ssize_t size_read; ssize_t size_written; char buffer[4096]; LOG(LOG_DEBUG, "read_from_write_to(): %d -> %d", from, to); size_read = read(from, buffer, sizeof(buffer)); if (0 > size_read) { LOG_PERROR(LOG_WARNING, "read_from_write_to(): read()"); return -1; } /* EOF */ if (0 == size_read) { return -1; } size_written = write(to, buffer, (size_t)size_read); if (0 > size_written) { LOG_PERROR(LOG_WARNING, "read_from_write_to(): write()"); return -1; } if (size_read != size_written) { LOG(LOG_ERROR, "read_from_write_to(): only written %ld of %ld bytes!", (long int)size_written, (long int)size_read); return -1; } return 0; } /* Transfer data between client and server TLS connection until one closes the * connection. */ static void transfer_data_tls(int client, int server, gnutls_session_t client_session, gnutls_session_t server_session) { size_t buffer_size; struct pollfd fds[2]; fds[0].fd = client; fds[0].events = POLLIN | POLLPRI | POLLHUP | POLLERR; fds[0].revents = 0; fds[1].fd = server; fds[1].events = POLLIN | POLLPRI | POLLHUP | POLLERR; fds[1].revents = 0; /* Get maximum possible buffer size. */ buffer_size = gnutls_record_get_max_size(client_session); if (buffer_size > gnutls_record_get_max_size(server_session)) { buffer_size = gnutls_record_get_max_size(server_session); } LOG(LOG_DEBUG, "transfer_data_tls(): suggested buffer size: %ld", (long int)buffer_size); for (;;) { int result = poll(fds, 2, -1 /* no timeout */); if (result < 0) { LOG_PERROR(LOG_ERROR, "transfer_data(): poll()"); return; } /* Data available from client. */ if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) { if (0 != read_from_write_to_tls(client_session, server_session, buffer_size)) { /* EOF (or other error) */ break; } } /* Data available from server. */ if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) { if (0 != read_from_write_to_tls(server_session, client_session, buffer_size)) { /* EOF (or other error) */ break; } } /* Client closed connection. */ if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) { break; } /* Server closed connection. */ if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) { break; } } } /* Read available data from session from and write to session to. */ static int read_from_write_to_tls(gnutls_session_t from, gnutls_session_t to, size_t buffer_size) { ssize_t size_read; ssize_t size_written; char buffer[16384]; if (buffer_size > sizeof(buffer)) { buffer_size = sizeof(buffer); } LOG(LOG_DEBUG, "read_from_write_to_tls(): used buffer size: %ld", (long int)buffer_size); size_read = gnutls_record_recv(from, buffer, buffer_size); if (0 > size_read) { LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_recv(): %s", gnutls_strerror((int)size_read)); return -1; } /* EOF */ if (0 == size_read) { return -1; } size_written = gnutls_record_send(to, buffer, (size_t)size_read); if (0 > size_written) { LOG(LOG_WARNING, "read_from_write_to_tls(): gnutls_record_send(): %s", gnutls_strerror((int)size_written)); return -1; } if (size_read != size_written) { LOG(LOG_ERROR, "read_from_write_to_tls(): only written %ld of %ld bytes!", (long int)size_written, (long int)size_read); return -1; } return 0; } static int connect_to_host(const char *hostname, const char *port) { struct addrinfo gai_hints; struct addrinfo *gai_result; int gai_return; int server_socket; struct addrinfo *server; if (NULL == hostname || NULL == port) { return -1; } /* Get IP of hostname server. */ memset(&gai_hints, 0, sizeof(gai_hints)); gai_hints.ai_family = AF_UNSPEC; gai_hints.ai_socktype = SOCK_STREAM; gai_hints.ai_protocol = 0; gai_hints.ai_flags = AI_NUMERICSERV /* given port is numeric */ | AI_ADDRCONFIG /* supported by this computer */ | AI_V4MAPPED; /* support IPv4 through IPv6 */ gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result); if (0 != gai_return) { LOG_PERROR(LOG_WARNING, "connect_to_host(): getaddrinfo()"); return -1; } /* Now try to connect to each server returned by getaddrinfo(), use the * first successful connect. */ for (server = gai_result; NULL != server; server = server->ai_next) { server_socket = socket(server->ai_family, server->ai_socktype, server->ai_protocol); if (-1 == server_socket) { LOG_PERROR(LOG_DEBUG, "connect_to_host(): socket(), trying next"); continue; } if (-1 != connect(server_socket, server->ai_addr, server->ai_addrlen)) { break; } LOG_PERROR(LOG_DEBUG, "connect_to_host(): connect(), trying next"); close(server_socket); } /* Make sure we free the result from getaddrinfo(). */ freeaddrinfo(gai_result); if (NULL == server) { LOG_PERROR(LOG_WARNING, "connect_to_host(): no server found, abort"); return -1; } return server_socket; } /* Parse HTTP CONNECT request string and save its parameters. * * The following format is expected: "CONNECT host:port HTTP/1.x". * * request and host must have the same size! port must be at least 6 bytes * long (5 + '\0'). */ static int parse_request(const char *request, char *host, char *port, int *version_minor) { int port_unused; /* just used to verify the port is numeric */ char *position; /* scanf() doesn't check spaces. */ if (0 != strncmp(request, "CONNECT ", 8)) { return -1; } /* Check request and extract data, "host:port" is not yet separated. */ if (2 != sscanf(request, "CONNECT %s HTTP/1.%d", host, version_minor)) { return -1; } /* Make sure ":port" is there. */ if (NULL == (position = strchr(host, ':'))) { return -1; } /* Make sure port is numeric. */ if (1 != sscanf(position + 1, "%d", &port_unused)) { return -1; } /* Store it in *port. */ strncpy(port, position + 1, 5); port[5] = '\0'; /* And remove port from host. */ *position = '\0'; return 0; }